A major study concludes that pesticides are overwhelmingly harming hundreds of species they aren’t meant to affect.
The systematic review analysed over 1700 experimental studies (including a handful from NZ). It found pesticides can reduce plant and animal growth, and affect animals’ ability to find a mate or catch prey. However, the researchers note that cutting pesticide use could affect global food supply and farmer livelihoods.
The SMC asked experts to comment.
Associate Professor Melanie Kah, School of Environment, University of Auckland, comments:
“I think this work is fantastic because it puts all the lines of evidence together, suggesting that pesticides are toxic. What’s important is the scale of the analysis. This review draws from 1700 studies, so it gives us a better feeling of what happens at the global scale, and the results clearly point towards negative effects of pesticides on non-target organisms.
“We need to improve the way we assess the risk associated with pesticides. In New Zealand, our regulatory framework is completely outdated. Some substances that have been phased out in Europe decades ago are still in use here, for instance. And I think we haven’t been given the resources by government to phase out those old substances and to consider newer chemistry.
“It’s a very short-term vision – pesticides increase productivity, no doubt. But in the longer term, this study shows that the price to pay as a society will probably be much higher. We are not only compromising the health of our ecosystems and people but also the reputation of New Zealand as a producer of high-quality, clean and green products. If there are excessive pesticide residues on the food that we want to export, that’s going to be an issue.
“This is a really key moment for New Zealand with the review of pesticide regulations underway. But we put it at risk by not investing adequate resources to hire more staff at the EPA, and by not funding monitoring programs to know where pesticides are applied and what their levels are in our water and soil. We are the only country in the OECD not keeping track of what pesticides are used in our country. That’s really shocking. This study just gives us another motivation to do something about it.
“Agriculture is responsible for most of the pesticide use in New Zealand. But this may also make individuals think twice before they use chemicals in their garden. It would be good if people at the personal, domestic level would realize that taking the synthetic pesticide path has impacts, not only in their own garden and their own health, but also beyond.”
Conflict of interest statement: Principal investigator of a scientific project funded by the Royal Society on “Building the foundation to improve the risk assessment of pesticides in Aotearoa/New Zealand.” The project ended in September 2024.
Dr Andrea Byrom, Independent Environmental Consultant and Director, comments:
“In a 2022 report on the fate of chemicals in the environment, the Parliamentary Commissioner for the Environment (PCE) noted that Aotearoa New Zealand has approved approximately 150,000 substances for use, made up of about 30,000 chemicals. So here in Aotearoa we should be very interested in the findings in this global meta-analysis: that there are strong negative effects of three classes of pesticides (insecticides, fungicides and herbicides) on the environment and on ecosystems, with potential consequences for biodiversity loss.
“Any global meta-analysis such as this is potentially useful. To me however this one stood out for several reasons. First, the authors were able to demonstrate significant effects on growth, reproduction and (in the case of animals) behaviour across a number of non-target plants and animals. These physiological effects potentially have far-reaching consequences for individual species and most likely add to a suite of threatening processes (others being the impact of invasive species or climate change) that put pressure on our native organisms, primary production sectors, and natural environments.
“Second, the authors tested whether their findings held for experimental field studies, not just studies under laboratory conditions. This is important, because what we really need to know is the impacts that pesticides might cause in the real world, not just in a lab. They found the same negative effects of pesticides on a range of species in the real world, which should be of concern both for our natural and primary production systems here in Aotearoa.
“Third, the authors went even further and tested whether their findings held for the sub-set of studies that investigated use of chemical pesticides under ‘field-realistic’ application rates. This is important too, because – despite the usually good intentions of those who use chemical pesticides – not all users adhere to recommended use or dosage conditions. This study demonstrates that even adhering to the recommended dosages and application rates still caused negative effects in non-target organisms in the field, which is again concerning.
“This study is a demonstration of just why the PCE’s recommendations back in 2022 – to help strengthen Aotearoa’s regulatory system so that we can understand the environmental fate of chemicals and their potential impacts – is so important. This study highlights that better surveillance, monitoring and reporting on the presence and quantity of chemicals such as pesticides in our environment would help us take a more holistic and systemic approach to the approval and use of chemicals in Aotearoa New Zealand.”
Conflict of interest statement: Andrea is a former member of the EPA Board and she chaired its Hazardous Substances and New Organisms (HSNO) Committee from 2021 to 2024. She is also a member of the Board of Manaaki Whenua Landcare Research.
Professor Amanda Black (Tūhoe, Whakatōhea, Te Whānau a Āpanui), Co-Director of Bioprotection Aotearoa, Lincoln University, comments:
“Pesticide use in New Zealand and other major food producing and exporting countries have been part of our integrated pest management for many decades. Some countries rely heavily on pesticides for several reasons – costs and a lack of any effective alternatives are the main driver. This is the consequence of having to convert large areas of land into monocultures – something that is irresistible to many invertebrates, or creating a new niche for weed and pathogen invasions.
“This systematic review finding that pesticides have a negative impact on biodiversity doesn’t come as a great surprise. Pesticides are designed to knock out their intended targeted groups such as insects, unwanted plants and pathogens that cause diseases. Pesticides do this through targeting biological processes critical to their survival. But within that group it isn’t specific. For example, the aerial spray for the painted apple moth in Auckland, more than 20 years ago was successful, but at the same time wiped out the local population of kahukura, our native red admiral butterfly.
“As a country we really need to properly invest in developing alternatives or bespoke pesticides to minimise these sorts of non-targeted effects which are widespread and impact on our ability to export our produce.”
No conflict of interest declared.
Dr David Wright, Science Team Leader – Microbial Solutions, AgResearch, comments:
“This article highlights the wide-ranging potential for negative impacts from synthetic pesticide use, and the urgency in which we need to adopt alternative practices that reduce those impacts.
“There is increasing interest and use of microbial technologies to complement, or provide alternatives to, synthetic chemistry. Bioprotectants containing live micro-organisms or derivatives such as peptides are considered safer alternatives as they are generally more specific to target pests and have a significantly shorter environmental residue.
“There are some excellent examples of microbial biopesticides under development, including AgResearch-developed AgR96X that contains a natural pathogen specific to the NZ grass grub and Manuka beetle. AgR96X has shown equivalence to registered synthetic products in field trials.
“While biopesticides offer promising alternatives, sometimes several products may be required to target multiple pests that are currently controlled by a single broad-spectrum agrichemical. Research is needed to incorporate these into production systems and a step change in thinking from the current reactive silver-bullet approach.
“We need to move to more integrated systems that incorporate an increased understanding of the pest/disease lifecycle and monitoring to predict outbreaks, along with the use of multiple technologies that include breeding for improved animal/plant genetics with resistance to pests and disease, changes to farm management practices, digital tools to identify areas of risk, and a move from broadacre treatment to targeted delivery of biopesticides and where necessary agrichemicals at significantly reduced volume.”
No conflict of interest.